U.S. patent number 5,306,758 [Application Number 08/067,634] was granted by the patent office on 1994-04-26 for fluorocarbon-based coating compositions and articles derived therefrom.
This patent grant is currently assigned to Minnesota Mining and Manufacturing Company. Invention is credited to Mark J. Pellerite.
United States Patent |
5,306,758 |
Pellerite |
April 26, 1994 |
**Please see images for:
( Certificate of Correction ) ** |
Fluorocarbon-based coating compositions and articles derived
therefrom
Abstract
Curable, crosslinkable compositions and coatings prepared
therefrom that can be used to form low-surface energy liners that
can be used with aggressive pressure-sensitive adhesives, such as
adhesives formed from silicone resins. The release characteristics
of these coatings do not diminish upon aging and do not adversely
affect the readhesion properties of adhesives that have-come in
contact with the coatings. The invention further provides
substrates bearing a layer of the composition of the invention.
These coated substrates are particularly suitable for release
liners, especially differential release liners and low-adhesion
backsizes for pressure-sensitive adhesive tapes and sheet
materials, especially for pressure-sensitive adhesives derived from
silicone resins. Because the coatings of this invention can have
more than 50% by weight inert oils without significantly reducing
the readhesion of adhesives removed from them, they provide an
economic advantage over those coatings prepared by using only the
more expensive reactive group-containing polyfluoropolyethers.
Inventors: |
Pellerite; Mark J. (St. Paul,
MN) |
Assignee: |
Minnesota Mining and Manufacturing
Company (St. Paul, MN)
|
Family
ID: |
23788851 |
Appl.
No.: |
08/067,634 |
Filed: |
May 26, 1993 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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450623 |
Dec 14, 1989 |
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Current U.S.
Class: |
524/366; 428/421;
428/422; 428/447; 428/354; 428/352; 524/373; 524/371; 428/355R;
428/40.7 |
Current CPC
Class: |
C09J
7/401 (20180101); C09D 171/02 (20130101); C08G
65/007 (20130101); C09D 171/02 (20130101); C08L
2666/22 (20130101); Y10T 428/2839 (20150115); Y10T
428/2848 (20150115); C09J 2301/414 (20200801); C09J
2427/005 (20130101); Y10T 428/1429 (20150115); Y10T
428/31663 (20150401); C09J 2471/005 (20130101); Y10T
428/3154 (20150401); Y10T 428/31544 (20150401); Y10T
428/2852 (20150115) |
Current International
Class: |
C09J
7/02 (20060101); C09D 171/02 (20060101); C09D
171/00 (20060101); C08G 65/00 (20060101); C08J
005/10 (); C08K 005/06 (); C08L 071/00 () |
Field of
Search: |
;524/366,371,373
;428/352,354,355,447,40,421,422 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
*Chemical Abstracts, vol. 113, No. 23, Dec. 3, 1990, Abstract No.
213979Q..
|
Primary Examiner: Michl; Paul R.
Assistant Examiner: Rajguru; U. K.
Attorney, Agent or Firm: Griswold; Gary L. Kirn; Walter N.
Weinstein; David L.
Parent Case Text
This is a continuation of application Ser. No. 07/450,623 filed
Dec. 14, 1989 now abandoned.
Claims
What is claimed is:
1. A composition suitable for preparing a release coating
comprising from about 15% by weight to about 67% by weight of a
polyfluoropolyether containing at least two reactive groups and
from about 33% by weight to about 85% by weight of an inert
polyfluoropolyether oil.
2. The composition of claim 1, wherein the inert
polyfluoropolyether has a viscosity of from about 20 to about 500
centipoise at 25.degree. C.
3. The composition of claim 1, wherein the inert
polyfluoropolyether has a viscosity of from about 90 to about 200
centipoise at 25.degree. C.
4. The composition of claim 1, wherein the polyfluoropolyether
containing at least two reactive groups is capable of crosslinking
or polymerizing or both.
5. The composition of claim 4, wherein the reactive groups of the
polyfluoropolyether is selected from the group consisting of
acrylate, hydrosilane, silanol, silalkoxy, epoxy, and
isocyanate.
6. The composition of claim 1, wherein the inert
polyfluoropolyether oil is: ##STR17## where n.congruent.13, 19, or
26.
7. The composition of claim 1, wherein the inert
polyfluoropolyether oil is: ##STR18## where n.congruent.25.
8. The composition of claim 1, wherein the inert
polyfluoropolyether oil is: ##STR19## where n.congruent.16
m.congruent.1
X represents CF.sub.3, C.sub.2 F.sub.5, C.sub.3 F.sub.7, or C.sub.4
F.sub.9.
9. A solution comprising the composition of claim 1 and a solvent
selected from the group consisting of evaporable fluorocarbons,
chlorofluorocarbons, and mixtures thereof, the viscosity of the
solution being sufficiently low to permit the deposition of a thin,
continuous coating upon a substrate.
10. A substrate bearing a coating formed from the composition of
claim 9, wherein said coating has been crosslinked by thermal or
actinic energy.
11. Tape comprising a backing bearing on one major surface thereof
a layer of pressure-sensitive adhesive and on the other major
surface thereof a release coating prepared from the composition of
claim 1.
12. The tape of claim 11, wherein said pressure-sensitive adhesive
comprises a silicone polymer.
13. The composition of claim 1, wherein the polyfluoropolyether
containing at least two reactive groups is ##STR20## where
m.congruent.12
n.congruent.10
and the inert polyfluoropolyether oil is ##STR21## where
n.congruent.13 or 19.
14. The composition of claim 1, wherein said polyfluoropolyether
having at least two reactive groups comprises from about 50% by
weight to about 67% by weight of said composition.
Description
BACKGROUND OF THE INVENTION
1. Field Of The Invention
This invention relates to release liners, and more particularly, to
release liners suitable for use with highly aggressive
pressure-sensitive adhesives.
2. Discussion of the Art
Pressure-sensitive adhesive tape, which is typically wound into
rolls, has a low-adhesion backsize coating applied to the major
surface of the backing not bearing adhesive to permit the tape to
be unwound without delamination and transfer of adhesive to the
surface of the backing not bearing adhesive. The force required to
separate the adhesive layer from the low-adhesion backsize coating,
i.e., peel force, ranges from 6 to 35 Newtons per decimeter (N/dm)
per unit width. If the tape is not wound into a roll, its adhesive
layer is customarily protected by a disposable web that bears a
low-adhesion coating to which normally tacky and pressure-sensitive
adhesives adhere very weakly, e.g., a peel force ranging from about
0.2 to about 6 N/dm, preferably 0.2 to 2 N/dm. Release coatings
having peel forces in this preferred range of 0.2 to 2 N/dm are
hereinafter referred to as "premium release" coatings.
Release coatings must both adhere strongly to the backing and be
sufficiently cured or rendered incompatible with the adhesive so
that it does not transfer to the adhesive layer and adversely
affect adhesive power of the adhesive. Low adhesion backsize
coatings having such properties are disclosed in U.S. Pat. Nos.
3,318,852; 3,536,749; 4,057,596; and 4,216,252.
Certain pressure-sensitive adhesives, particularly those derived
from silicone resins, are so aggressive that tapes employing them
exhibit undesirably high peel forces upon removal from known
low-adhesion coatings, especially after prolonged storage or when
used in a high-temperature environment. The adhesive of such tapes
may carry away, and consequently, be contaminated by appreciable
amounts of the low-adhesion material. If this occurs, the tapes
will exhibit poor readhesion when applied to "end-use" receptor
surfaces.
Known low-adhesion coatings, e.g. poly(urethanes),
poly(tetrafluoroethylenes), and poly(dimethylsiloxanes), do not
provide release peel forces in the range 0.2 to 2 N/dm when used
with poly(dimethylsiloxane) adhesives.
The utility of polymeric fluorocarbons as release coatings has been
disclosed in U.S. Pat. Nos. 4,472,480; 4,567,073; and 4,614,667.
Uncrosslinked fluorinated waxes and oils are frequently used as
lubricants and mold release agents in applications where low
adhesion coatings are designed to fail cohesively within the bulk
phase. Conversely, crosslinked fluorinated waxes and oils are
preferred when it is desired to avoid cohesive failure of release
liners. Examples of crosslinking reactions that have been used to
prepare low energy release liners are photochemical crosslinking,
described in U.S. Pat. Nos. 4,472,480; 4,567,073; and 4,614,667;
thermal crosslinking of silicone resins, described in U.S. Pat. No.
4,472,480; and chemical crosslinking of silicone resins
(hydrosilation), described in U.S. Pat. No. 4,565,741. U.S. Pat.
No. 4,321,404 describes abherent coatings made by using electron
beam radiation to polymerize a mixture of film-forming and
polyfluorinated oligomers in a single step. The mixture is
formulated so that the fluorinated materials tend to segregate at
the coating surface, i.e., the air interface, so that the abherent
coating can be crosslinked with a single pass through the electron
beam curtain. These coating,#have excellent readhesion; however,
they were formulated for use with acrylic adhesives and typically
have high release values when used with these adhesives. These
release values would be higher still if these abherent coatings
were used with the highly aggressive silicone pressure-sensitive
adhesives.
In order to further reduce the possibility of cohesive failure, a
crosslinked primer coating to securely anchor the release coating
to its backing has been used. U.S. Pat. Nos. 4,567,073 and
4,614,667 disclose the advantage of first photopolymerizing a thin
layer of a film-forming polymer that is strongly bonded to the
surface of a substrate. This primer layer is also capable of
subsequently reacting with functional groups attached to a
polyfluoropolyether, which is applied as a second thin layer over
the photopolymerized layer, thereby chemically bonding the release
coating to the inner primer layer. These release liners exhibit
release of about 0.6 N/dm, and excellent readhesion for certain
classes of silicone-based pressure-sensitive adhesives.
SUMMARY OF THE INVENTION
The present invention provides curable, crosslinkable compositions
and coatings prepared therefrom that can be used to form
low-surface energy liners that can be used with aggressive
pressure-sensitive adhesives, such as adhesives formed from
silicone resins. The release characteristics of these coatings do
not diminish upon aging and do not adversely affect the readhesion
properties of adhesives that have come in contact with the
coatings.
Briefly, the compositions of the present invention comprise a
crosslinkable polyfluoropolyether and an inert polyfluoropolyether
oil. The compositions can be dissolved in mixtures of fluorinated
solvents in order to provide solutions having a viscosity suitable
for coating by methods well known in the art.
The composition preferably contains from about 15 to about 90% by
weight crosslinkable polyfluoropolyether, more preferably from
about 50 to about 85% by weight, and from about 10 to about 85% by
weight inert polyfluoropolyether oil. It is preferred that the
polyfluoropolyether oil have a viscosity from about 20 to about 500
centipoise at 25.degree. C., more preferably from about 90 to about
200 centipoise at 25.degree. C.
The invention further provides substrates bearing a layer of the
composition of the invention. These coated substrates are
particularly suitable for release liners, especially differential
release liners and low-adhesion backsizes for pressure sensitive
adhesive tapes and sheet materials, especially for
pressure-sensitive adhesives derived from silicone resins.
Likewise, the release coatings of this invention are specifically
formulated and cured to resist cohesive failure within the bulk
phase but to fail uniformly along an extremely thin, weak boundary
layer at the release coating-adhesive interface.
It has been found that silicone adhesives on the fluorochemical
release liners of the present invention will not suffer dramatic
reductions of the readhesion value, as will acrylic adhesives on
silicone-based release liners if uncured material is present.
Surprisingly, pressure-sensitive adhesives in contact with the
release liners of the present invention can have very high
readhesion values--in excess of 90% of those of control adhesives
which have not been in contact with any release coating or liner.
Such high readhesion values are indicative of little, if any,
transfer of fluorocarbon materials of low surface energy to the
pressure-sensitive adhesive. Because the coatings of this invention
can have more than 50% by weight inert oils without significantly
reducing the readhesion of adhesives removed from them, they
provide an economic advantage over those coatings prepared by using
only the more expensive reactive group-containing
polyfluoropolyethers.
DETAILED DESCRIPTION OF THE INVENTION
The reactive group-containing, crosslinkable polyfluoropolyethers
suitable for use in this invention are represented by the general
formula: ##STR1## wherein Z represents a terminal group that either
contains a functional moiety that can enter into an addition or
condensation reaction to form a polymer or an inert moiety
incapable of entering into a reaction to form a polymer;
Z' represents a terminal group that contains a functional moiety
that can enter into an addition or condensation reaction to form a
polymer;
each R.sup.1 independently represents a fluorine or a
perfluoroalkyl group that can be linear, branched, or cyclic;
each OR.sup.2 independently represents a perfluoroalkoxy group
wherein R.sup.2 represents a perfluoroalkyl group or a
perfluoroalkyl group substituted with one or more ether oxygen
atoms, independently selected from the units having the structure
--(R.sup.3 O.sub.f --R.sup.4, in which each R.sup.3 is
independently selected from --CF.sub.2, --CF.sub.2 CF.sub.2 --, and
##STR2## and R.sup.4 represents a perfluoroalkyl group selected
from linear, branched, and cyclic groups,
f is zero or a number having a value of 1 to 6,
g is a number representing the average number of --CF.sub.2 O--
units randomly distributed within the chain and has a value of zero
or greater,
h is a number representing the average number of ##STR3## units
randomly distributed along the chain and has value of 1 or greater;
i and i' can be the same or different and each is a number
representing the number of ##STR4## units, respectively,
distributed within the chain, the sum of i and i' having a value of
0 or greater and the ratio i/i' being 0 to 5;
the ratio of g/h being less than 10;
the ratio of (i+i')/(g+h) being 0.0 to 1.5; and
the number average molecular weight of the polyfluoropolyether
being from about 640 to 20,000.
Especially useful in the practice of this invention are
polyfluoropolyether polymers having non-perfluorinated,
crosslinkable end groups such as acrylate, isocyanato, or
bis(amidopropyltriethoxysilane). Examples of structures of such
polymers are as follows: ##STR5## Many other combinations of
crosslinkable end groups and polyfluoropolyether polymer backbones
are useful in this invention.
The general formula for inert polyfluoroether oils are represented
by the general formula: ##STR6## wherein each x independently
represents hydrogen or halogen, provided that when X represents
hydrogen, then j is 1 or 2, and when X represents halogen, then j
is an integer of form 1 to 5;
R.sup.1, OR.sup.2, R.sup.3, R.sup.4, f, g, h, i, i' are as defined
previously;
k represents 3 or 4; and
1 represents 1 or a number greater than 1.
Examples of inert polyfluoropolyether fluids useful in the practice
of this invention include those designated by the trade names
"Krytox" 1506, "Krytox" 1514, "Krytox" 1645, commercially available
from E. I. DuPont de Nemours and Company, "Demnum" fluids,
commercially available from Daikin, and "Fomblin" Y and "Fomblin" Z
fluids, commercially available from Montecatini-Edison.
Examples of structures of such polymers are as follows:
"Krytox" fluids: ##STR7## where n.congruent.13 (for "Krytox"
1506)
n.congruent.19 (for "Krytox" 1514)
n.congruent.26 (for "Krytox" 1645)
"Demnum" S-65 fluid: ##STR8## where
n.apprxeq.25
"Fomblin" Y fluids: ##STR9## where n.congruent.16
m.congruent.1
X represents CF.sub.3, C.sub.2 F.sub.5, C.sub.3 F.sub.7, or C.sub.4
F.sub.9
"Fomblin" Z fluid: ##STR10## where n.congruent.10 to 100
m.congruent.10 to 100
X, Y.sup.1 independently represent CF.sub.3, C.sub.2 F.sub.5,
CF.sub.2 Cl, or CF.sub.2 CF.sub.2 Cl
Hydrogen-terminated perfluoropolyether ##STR11## where
n.congruent.10
m.congruent.12
As used herein, the values of m and n represent averages for a
distribution of structures. The symbol ".congruent." means
approximately equals.
Many other inert fluids derived from polyfluoropolyether polymers
are useful in this invention.
Examples of catalysts and initiators that can be used to crosslink
the components of the composition of this invention include
dibutyltin diacetate, benzildimethylketal, perfluoroalkylcarboxylic
acids, sulfonic acids, and
2-hydroxyl-2-methyl-1-phenylpropane-1-one ("Darocur" 1173,
available from EM Industries, Inc.).
Solvents that can be used for applying the composition of this
invention include mixtures of the "Freon" series, e.g.,
1,1,2-trichlorotrifluoroethane, the "FC" series of perfluorinated
hydrocarbons, e.g., perfluorooctane, hexafluoroxylene, and
trifluorotoluene.
The composition of this invention can be applied to a substrate to
form a low energy surface liner by the following process:
(a) providing a solution comprising the functional
polyfluoropolyether, the inert polyfluoropolyether, a catalyst for
the crosslinking reaction, and a mixture of fluorinated
solvents,
(b) coating the solution onto a substrate,
(c) curing the coated composition either thermally or by
irradiation depending on the nature of the curing agent, for a
suitable period of time, typically ranging from a fraction of a
second to five minutes or more.
Substrate shapes that are suitable for the composition of the
present invention include sheets, fibers, and materials of other
shapes. Preferred substrate materials include flexible sheet
materials that are used as backings for pressure-sensitive adhesive
products, such as, for example, polyester, polyimide, polyamide,
polyolefin, and polycarbonate films. Other substrate materials that
are suitable for the composition of this invention include glass,
ceramic, metal, and rubber.
The coating techniques that are useful for applying the composition
of this invention include brushing, wire-wound rod or knife
coating, spraying, curtain coating, and gravure coating.
In some cases, it may be desirable to first apply to the substrate
a primer or an adhesion-promoting coating or to treat the
substrate. Such treatments are described in U.S. Pat. Nos.
4,567,073 and 4,614,667.
A substrate bearing a coating of the cured composition of the
invention on one or both major surfaces thereof can then be coated
with any adhesives known in the art, such as, for example, acrylic
adhesives, rubber-based adhesives, and silicone-based adhesives.
The adhesive-coated substrate can then be wound up into a roll, if
desired. Flexible, pressure-sensitive adhesive-coated sheet
materials are well known in the art. See, for example, U.S. Pat.
Re. 24,906 (acrylate), U.S. Pat. Nos. 2,857,356; 2,814,601; and
2,736,721 (siloxane), and U.S. Pat. No. 3,925,283 (urethane).
The releasability of the coatings of this invention with respect to
adhesives can be measured by various methods known in the art. The
method selected depends upon whether the final product is in sheet
or roll form, such as a tape. Various methods for testing
pressure-sensitive tapes are reported by the Pressure-Sensitive
Tape Council (PSTC) in "Test Methods for Pressure-Sensitive
Tapes".
The release values of the cured polyfluoropolyether-coated
substrates prepared in the following examples were determined as
follows:
Dry Laminate Adhesives
A strip of tape bearing a layer of polysiloxane adhesive was
pressed against the surface of a polyfluoropolyether coating under
the weight of a 2.3 kg rubber roller to produce a laminate
consisting of pressure-sensitive adhesive tape and a
polyfluoropolyether-coated substrate. The laminate is then
subjected to heat aging. The release value is the force required to
separate the layer of adhesive from the release-coated substrate at
a peel angle of 180.degree. and a peel rate of 230 cm/min.
Adhesives Cast From A Solvent
The adhesive was applied to a polyfluoropolyether-coated substrate
by means of a knife coater or other suitable coating device, dried,
and cured if required. The exposed surface of the layer of adhesive
was then laminated to a polyester film having a thickness of 50
micrometers. Strips having a width of 2.5 cm were cut from this
laminate, and the release value was measured as described
above.
The readhesion value of the pressure-sensitive tape was determined
as follows:
After being removed from the polyfluoropolyether-coated substrate,
the pressure-sensitive adhesive was applied to the surface of a
clean glass plate by means of a 2.3 kg rubber roller. The
readhesion value is a measure of the force required to pull the
tape from the glass surface at an angle of 180.degree. at a rate of
230 cm/min.
Advantages of this invention are further illustrated by the
following examples, but the particular materials and amounts
thereof recited in these examples, as well as other conditions and
details, should not be construed to unduly limit this invention. In
the following examples, all values of m and n are average
values.
EXAMPLE 1
This example demonstrates the effect of inert fluid on the release
and readhesion performance of coatings prepared from "Krytox" 1506
polyfluoropolyether fluid or "Krytox" 1514 polyfluoropolyether
fluid and a polyfluoropolyether bis(triethoxysilane)(hereinafter
Compound I). ##STR12##
Five coating solutions comprising 6% by weight of a mixture of
polyfluoropolyether bis(triethoxysilane) (Compound I) and
perfluoropolyether fluid in a solvent comprising 40% by volume
1,1,2-trichlorotrifluoroethane ("Freon" 113) and 60% by volume
perfluorooctane ("IFC-75")were prepared.
In the five coating solutions, the ratio by weight of
polyfluoropolyether bis(triethoxysilane) to polyfluoropolyether
fluid was 95:5, 90:10; 85:15, 80:20, and 70:30. The
polyfluoropolyether fluids used were "Krytox" 1506 and "Krytox"
1514 fluids.
A cure catalyst, dibutyltin diacetate (2% by weight, based on total
polyfluoropolyether charge), was added to each solution. Release
liners were made by coating the aforementioned solutions onto
polyethylene terephthalate films (50 micrometers thick) by means of
a #4 mayer bar, thereby producing coatings having a nominal coating
thickness of 0.5 micrometers. The liners were cured for about 16
hours at about 25.degree. C. The cured liners were laminated to 2.5
cm wide strips of adhesive tape having an aggressively tacky
methylsilicone pressure-sensitive adhesive ("MacDermid" MACU Tape
P-3) by pressing the adhesive into contact with the liner by means
of a 2.3 kg rubber roller. The initial values of "Release Peel
Force", "Readhesion Peel Force" and "Control Peel Force" were
measured by means of a peel tester (3M Model 90, available from
Instrumentors, Inc.). The 180.degree. peel force was measured at a
peel rate of 230 cm/min. After being peeled off the liner, the
pressure-sensitive adhesive was immediately readhered to a clean
glass plate by means of a 2.3 kg hard rubber roller (two passes),
and the 180.degree. peelback force (the "Readhesion Peel Force")
was again measured at a peel rate of 230 cm/min.
Another piece of the test tape was adhered to a clean glass plate
and tested in the same way as in the previous test to provide the
"Control Peel Force". The reduction in "Readhesion Peel Force"
versus "Control Peel Force" was presumed to result from transfer of
liner material to the pressure-sensitive adhesive. Some of the
laminates were aged for 72 hours at 70.degree. C. prior to testing.
The test results are set forth in Table I.
TABLE I ______________________________________ Ratio of Release
"Krytox" Compound I force Readhesion.sup.a designation to fluid
(N/dm) (N/dm) ______________________________________ -- 100:0 20.4
30.9 1506 95:5 15.5 32.1 1506 90:10 10.3 31.9 1506 85:15 1.2 42.0
1506 80:20 1.1 42.2 1506 70:30 0.4 35.4 1514 95:5 1.2 41.1 1514
90:10 0.8 43.0 1514 85:15 0.4 40.6 1514 80:20 0.3 37.0 1514 70:30
0.2 32.7 ______________________________________ .sup.a Control
readhesion for fresh adhesive was approximately 39 N/dm. A used
herein, "control readhesion" means the adhesion of an adhesive that
has never been in contact with a release liner.
EXAMPLE 2
This example demonstrate preparation of release coatings for
solvent-cast silicone adhesives. Release liners were applied to PET
film (50 micrometers) by means of coating with a #4 R.D.S.
wire-wound rod a solution containing 6% by weight of a mixture of
83% by weight polyfluoropolyether bis(triethoxysilane) (Compound I)
and 17% by weight "Krytox" 1506 fluid in a solvent containing 40%
by volume 1,1,2-trichlorotrifluoroethane ("Freon" 113) and 60% by
volume perfluorooctane ("FC-75"). The solution also contained 4% by
weight dibutyltin diacetate (based on total polyfluoropolyether
charge). The coatings were allowed to cure overnight in air at room
temperature. Wet-cast silicone adhesive DC-355 and GE-6574 were
applied to the release coatings under the conditions specified in
Table II. After the adhesive had dried and cured, it was laminated
to PET film (50 micrometers). Pieces of the laminates of 2.5 cm
width were cut for release and readhesion measurements. These
measurements were made by means of the procedures described in
Example 1. The results are set forth in Table II.
TABLE II ______________________________________ Release (N/dm)
Readhesion (N/dm).sup.a Adhesive Initial Aged Initial Aged
______________________________________ DC-355 0.2.sup.b 0.3.sup.b
63.2.sup.b 64.2.sup.b 0.5.sup.d 11.9.sup.d 66.9.sup.d 61.5.sup.d
GE-6574 0.3.sup.c 0.2.sup.c 99.6.sup.c 100.1.sup.c 25.6.sup.e --
82.7.sup.e -- ______________________________________ .sup.a Control
readhesion for fresh adhesives: DC355, approximately 82 N/dm;
GE6574, approximately 100 N/dm. .sup.b The adhesive was coated from
18% by weight solution in 1,1,2trichlorotrifluoroethane ("Freon"
113), at a wet film thickness of 250 micrometers. The coating was
dried 24 hours at room temperature, no catalyst was used. Initial
release measurements were made after heating the laminates for 24
hours at 70.degree. C.; aged release measurements were made after 7
days at 70.degree. C. .sup.c The adhesive was coated from 33% by
weight solution of toluene/xylene with 2% by weight (based on
silicone) "Cadox TS50" initiator, at a wet film thickness 300
micrometers. The coating was dried at 70.degree. C. for 10 minutes,
then cured for 5 minutes at 150.degree. C. Initial release
measurements were made shortly after laminating; aged release
measurements were made after heating the laminates for 3 days at
70.degree. C. .sup.d These values were obtained using release
coatings prepared from coating solutions identical to those
described in note b, except with 6% by weight compound I (no
"Krytox" 1506 fluid present). .sup.e These values were obtained
using release coatings prepared from coating solutions identical to
those described in note c, except with 6% by weight compound I (no
"Krytox" 1506 fluid present).
EXAMPLE 3
This example demonstrates the preparation of release coatings
having a high content of inert perfluoropolyether fluid.
Six coating solutions consisting of 1.1% by weight mixtures of
polyfluoropolyether bis(triethoxysilane) (Compound I) and "Krytox"
1514 fluid in a solvent containing 40% by volume
1,1,2-trichlorotrifluoroethane ("Preon" 113) and 60% by volume
perfluorotributylamine ("FC-43") were prepared. In the six coating
solutions, the ratio by-weight of polyfluoroether
bis(triethoxysilane) to "Krytox" fluid was 50:50, 25:75, 15:85,
10:90, 5:95, and 0:100. The solutions also contained 4% by weight
(based on total polyfluoropolyether charge) dibutyltin diacetate as
cure catalyst. These solutions were coated onto PET film (50
micrometers) by means of a #4 R.D.S. wire-wound rod. The coated
films were heated at 110.degree. C. for one minute and allowed to
stand at room temperature in air for several hours. The coatings
were tested with MacDermid P-3 and DC-355 silicone adhesives by
means of the procedures described in Examples 1 and 2, and initial
release, release after aging, and readhesion values were measured.
The results are set forth in Table III.
TABLE III ______________________________________ Percent (wt)
"Krytox" Release (N/dm) Readhesion (N/dm).sup.a 1514 fluid Adhesive
Initial Aged Initial Aged ______________________________________ 50
MacDermid 0.3 0.7 33.7 35.3 50 DC-355 0.2 0.3 73.8 72.4 75
MacDermid 0.3 0.3 33.8 33.5 85 MacDermid 0.2 0.2 32.5 33.1 85
DC-355 0.4 0.3 74.7 75.4 90 MacDermid 0.3 1.0 32.0 30.4 90 DC-355
10.4 -- 67.0 -- 95 MacDermid 0.8 10.3 31.1 21.4 95 DC-355 15.9 --
68.9 -- 100 MacDermid 31.2 35.7 20.9 22.0 100 DC-355 78.4 82.2 25.5
38.3 ______________________________________ .sup.a Control
readhesion for fresh adhesives: "MacDermid" P3, approximately 35
N/dm; DC355, approximately 82 N/dm.
EXAMPLE 4
This example demonstrates the effect of concentration of inert
perfluoropolyether fluid on performance of release coatings with a
solvent-cast peroxide cured adhesive.
Three coating solutions comprising 1.1% by weight mixtures of
polyfluoropolyether bis(triethoxysilane) (Compound I) and "Krytox"
1514 fluid, were prepared. In the three coating solutions, the
ratio by weight of polyfluoropolyether bis(triethoxysilane) to
polyfluoropolyether fluid was 83.j:16.7, 75:25, and 67:33. The
solution also contained 4% by weight (based on total
polyfluoropolyether charge) dibutyltin diacetate as the cure
catalyst. These solutions were coated onto PET film (50
micrometers) by means of a #4 R.D.S. wire-wound rod. The coatings
were cured at 110.degree. C. for one minute and then allowed to
stand overnight in air at room temperature.
Silicone adhesive (DC-7406)(33% by weight solids in toluene) with
2% by weight (based on silicone solids) initiator ("Cadox TS-5011)
was applied to the release coatings by means of a knife coater (300
micrometers orifice). The adhesive was dried at 70.degree. C. for
10 minutes, cured at 150.degree. C. for five minutes, and laminated
to PET film (50 micrometers). Strips of 2.5 cm width were cut for
peel test measurements. Initial release, release upon aging
(70.degree. C. for 72 hours) and readhesion were evaluated by the
procedures described in Example 1. The results are set forth in
Table IV.
TABLE IV ______________________________________ Weight Ratio of
Compound I to "Krytox" 1514 Release (N/dm) Readhesion (N/dm).sup.a
fluid Initial Aged Initial Aged
______________________________________ 83.3:16.7 0.7 27.8 65.0 57.0
75:25 1.2 19.1 73.5 64.4 67:33 0.9 1.1 79.7 82.3
______________________________________ .sup.a Control readhesion
for fresh adhesive, approximately 77 N/dm
EXAMPLE 5
Release coatings were prepared according to the procedures used in
Example 4 from 1.1% by weight solutions of mixtures of
polyfluoropolyether bis(triethoxysilane) (Compound I) and various
polyfluoropolyether inert fluids. Solvent, catalyst, coating
conditions, and curing conditions used were identical to those used
in Example 4. The coatings were tested according to the procedures
described in Examples 1 and 2. The coatings were laminated with
silicone adhesives ("MacDermid" P-3 and DC-355), and initial
release, release after aging, and readhesion values were measured.
The results are set forth in Table V.
TABLE V ______________________________________ Weight ratio of
Release Readhesion Compound (N/dm) (N/dm).sup.a Inert I to Ad- Ini-
Ini- fluid inert fluid hesive tial Aged tial Aged
______________________________________ "Demnum" 67:33 "Mac- 0.6 1.6
32.8 32.6 S-65 Dermid" "Demnum" 67:33 DC-355 0.3 0.3 68.1 69.1 S-65
PPE(H).sub.2.sup.b 67:33 "Mac- 0.4 0.6 35.4 -- Dermid"
PPE(H).sub.2.sup.b 67:33 DC-355 0.2 0.2 84.6 87.5 "Krytox" 75:25
"Mac- 1.5 2.5 40.5 36.7 1645 Dermid" "Krytox" 75:25 DC-355 1.6 2.4
69.5 66.8 1645 ______________________________________ .sup.a
Control readhesion for fresh adhesives: "MacDermid" P3,
approximately 34 to 39 N/dm, some variation between lots. DC355, 82
to 93 N/dm, some variation between lots. .sup.b PPE(H).sub.2 is an
abbreviation for hydrogenterminated perfluoropolyether.
EXAMPLE 6
A release coating was prepared according to the procedure described
in Example 5 from a 1.1% by weight solution of a mixture of
polyfluoropolyether bis(triethoxysilane) (Compound I) and
"Braycote" 815Z inert polyfluoropolyether fluid. The weight ratio
of Compound I to the inert fluid was 67:33. Solvent, catalyst,
coating conditions, and curing conditions were identical to those
of Example 5. The coating was tested with silicone adhesives
("MacDermid" P-3 and DC-355) by means of procedures described in
Examples 1 and 2, and initial readhesion and readhesion after aging
were measured. The results are set forth in Table VI.
TABLE VI ______________________________________ Release (N/dm)
Readhesion (N/dm).sup.a Adhesive Initial Aged Initial Aged
______________________________________ "MacDermid" 5.1 15.1 31.8
24.2 DC-355 2.7 4.9 63.6 65.5
______________________________________ .sup.a Control readhesion
for fresh adhesives: "MacDermid" P3, approximately 35 N/dm; DC355,
approximately 82 N/dm
EXAMPLE 7
This example involves preparation of a release coating using a
mixture of monofunctional and difunctional reactive materials.
A coating solution (hereinafter Solution A) consisting of 1.1% by
weight of a mixture of polyfluoropolyether bis(triethoxysilane)
(Compound I), polyfluoropolyether triethoxysilane (Compound II)
(n=10), and "Krytox" 1514 fluid, was prepared. ##STR13##
The weight ratio of Compound I to Compound II to the inert fluid
was 1:1:1. Solution A also contained 4% by weight (based on total
polyfluoropolyether charge) dibutyltin diacetate as cure catalyst.
The solvent consisted of 40% by volume
1,1,2-trichlorotrifluoroethane ("Freon" 113) and 60% by volume
perfluorotributylamine ("FC-43").
A second coating solution (hereinafter Solution B) was prepared in
a manner identical to that used to prepare Solution A. Solution B
consisted of a 1.1% by weight solution of a mixture of Compound I
and Compound II in a solvent consisting of 40% by volume
1,1,2-trichlorotrifluoroethane ("Freon" 113) and 60% by volume
perfluorotributylamine ("FC-43"). The ratio by weight of Compound I
to Compound II was 1:1. No "Krytox" 1514 fluid was added to
Solution B. These solutions were coated onto PET film (50
micrometers) by means of a #4 R.D.S. wire-wound rod, heated at
110.degree. C. for one minute, then allowed to age in air at room
temperature for one week. The coatings were laminated and tested
with adhesive tape ("MacDermid" P-3) as described in Example 1. The
results from peel measurements are set forth in Table VII.
TABLE VII ______________________________________ Release (N/dm)
Readhesion (N/dm).sup.a Solution Initial Aged Initial Aged
______________________________________ A 3.4 6.9 33.5 31.5 B 25.2
27.8 27.4 26.2 ______________________________________ .sup.a
Control readhesion for fresh adhesive, approximately 35 N/dm
EXAMPLE 8
Coating solutions containing 1.0% by weight of mixtures of
polyfluoropolyether bis(triethoxysilane) (Compound I) and "Krytox"
1514 fluid were prepared. The solvent consisted of 40% by volume
1,1,2-trichlorotrifluoroethane ("Freon" 113) and 60% by volume
perfluorotributylamine ("FC-43"). The solutions also contained 4%
by weight (based on total polyfluoropolyether charge) dibutyltin
diacetate. These solutions were coated on polyimide film
("Kapton")(25 micrometers) by means of a #4 R.D.S. wire-wound rod,
and cured at 110.degree. C. for 10 minutes. After the coatings had
cooled, they were laminated to strips of silicone ;adhesive tape
(3M #92, Minnesota Mining and Manufacturing Company) by means of a
2.3 kg rubber roller. The laminates were aged at 130.degree. C. for
17 hours before they were tested for release and readhesion values
according to the procedures described in Example 1. The results are
set forth in Table VIII.
TABLE VIII ______________________________________ Weight ratio of
Compound I to "Krytox" 1514 fluid Release (N/dm) Readhesion
(N/dm).sup.a ______________________________________ 100:0 20.5 26.5
90:10 15.7 25.4 80:20 13.6 24.5 70:30 5.5 25.2
______________________________________ .sup.a Control readhesion
for fresh adhesive, approximately 26 N/dm
EXAMPLE 9
This example describes the preparation of ultraviolet
radiation-cured release coating prepared from "Krytox" 1514 fluid
and polyfluoropolyether diacrylate (Compound III). ##STR14##
Coating solutions consisting of 1.1% by weight of 100%
polyfluoropolyether diacrylate (Compound III) and a mixture of 67%
by weight Compound III and 33% by weight "Krytox" 1514 fluid in a
solvent consisting of 40% by volume 1,1,2-trichlorotrifluoroethane
("Freon" 113) and 60% by volume perfluorotributylamine ("FC-43")
were prepared.
These solutions were coated onto PET film (50 micrometers) by means
of a #4 wire-wound rod. Curing was effected by two passes of each
coated substrate through a PPG Model 1202 ultraviolet processor at
a line speed of 20 re/min, in a nitrogen atmosphere, and at a high
lamp power. The coatings were laminated to silicone adhesive tape
("MacDermid" P-3) and the laminates were tested for release and
readhesion values according to the procedures described in Example
1. The results are set forth in Table IX.
TABLE IX ______________________________________ Weight ratio of
Compound I to "Krytox" 1514 Release (N/dm) Readhesion (N/dm).sup.a
fluid Initial Aged Initial Aged
______________________________________ 67:33 0.3 0.8 32.6 28.7
100:0 2.7 20.7 36.5 24.9 ______________________________________
.sup.a Control readhesion for fresh adhesive, approximately 35
N/dm
EXAMPLE 10
This example describes the preparation of ultraviolet
radiation-cured release coatings with added photoinitiator.
Three coating solutions consisting of 6.0% by weight of mixtures of
polyfluoropolyether diacrylate (Compound III) and "Krytox" 1514
fluid, along with 2% by weight (based on total polyfluoropolyether
charge) "Darocur" 1173 photoinitiator, in
1,1,2-trichlorotrifluoroethane ("Freon" 113) were prepared. The
ratio by weight of Compound III to "Krytox" 1514 fluid in the three
mixtures was 100:0, 85:15, and 70:30. The coatings were applied,
cured, and tested in accordance with the procedures described in
Example 9. The results are set forth in Table X.
TABLE X ______________________________________ Weight ratio of
Compound I to "Krytox" 1514 Release (N/dm) Readhesion (N/dm).sup.a
fluid Initial Aged Initial Aged
______________________________________ 85:15 0.3 1.4 34.1 33.2
70:30 0.2 0.5 33.0 29.5 100:0 0.2 17.0 37.8 26.0
______________________________________ .sup.a Control readhesion
for fresh adhesive, approximately 35 N/dm
EXAMPLE 11
This example describes preparation of release coatings based on
urethane-cure chemistry.
A coating solution (hereinafter Solution C) was prepared by mixing,
in a vial, polyfluoropolyether diol (Compound IV) (0.85 g),
toluenediisocyanate (0.12 g), "Krytox" 1514 fluid (0.32 g), and
1,1,2-trichlorotrifluoroethane ("Freon" 113) (20.2 g).
##STR15##
After the mixture was shaken to form a solution, dibutyltin
diacetate (0.022 g) was added thereto. A coating solution
(hereinafter Solution D) was prepared by mixing, in a vial,
polyfluoropolyether diol (Compound IV) (1.13 g),
toluenediisocyanate (0.16 g), and 1,1,2-trichlorotrifluoroethane
("Freon" 113) (20.2 g). After the mixture was shaken to form
Solution D, dibutyltin diacetate (0.022 g) was added thereto.
Solution C and Solution D were coated on PET film (50 micrometers)
by means of a #4 R.D.S. wire-wound rod, and the coatings were cured
at 110.degree. C. for five minutes. After the coatings aged
overnight in air at room temperature, they were tested with
silicone adhesive (DC-355) according to procedures described in
Example 2. Release and readhesion results are set forth in Table
XI.
TABLE XI ______________________________________ Release (N/dm)
Readhesion (N/dm).sup.a Coating Initial Aged Initial Aged
______________________________________ Solution C 1.4 2.0 60.2 58.1
Solution D 32.5 49.4 58.3 53.3
______________________________________ .sup.a Control readhesion
for fresh adhesive, approximately 82 N/dm
EXAMPLE 12
This example describes the use of a polyurethane substrate.
A coating solution (hereinafter Solution E) was prepared by mixing,
in a vial, polyfluoropolyether diol (Compound IV) (0.88 g),
toluenediisocyanate (0.15 g), "Krytox" 1514 fluid (0.26 g), and
1,1,2-trichlorotrifluoroethane.("Freon" 113) (20.15 g). After the
mixture was shaken to form a solution, dibutyltin diacetate (0.052
g) was added. A coating solution (hereinafter Solution F) was
prepared in the same way from polyfluoropolyether diol (Compound
IV) (1.10 g), toluenediisocyanate (0.19 g),
trichlorotrifluoroethane ("Freon" 113) (20.15 g), and dibutyltin
diacetate (0.052 g). These solutions were coated on "Gravel Guard"
polyurethane film by means of a #4 R.D.S. wire-wound rod. The
coatings were cured at 1100C for five minutes, then allowed to age
overnight in air at room temperature. They were laminated to strips
of silicone adhesive tape ("MacDermid" P-3), and the laminates were
tested to determine initial release, release after aging, and
readhesion according to the procedures described in Example 1. The
results are set forth in Table XII.
TABLE XII ______________________________________ Release (N/dm)
Readhesion (N/dm).sup.a Coating Initial Aged Initial Aged
______________________________________ Solution E 0.2 6.6 33.5 23.5
Solution F 21.9 38.1 27.7 22.7
______________________________________ .sup.a Control readhesion
for fresh adhesive, approximately 35 N/dm
EXAMPLE 13
This example describes the overcoating of inert fluid on a coating
of the curable component.
Polyfluoropolyether bis(triethoxysilane) (Compound I) was coated
onto PET film (50 micrometers) and cured in the identical manner as
described in-Example 1. After the coating was cured overnight at
room temperature, it was overcoated with a solution of 1% by weight
"Krytox" 1506 fluid in perfluorooctane ("FC-75") by means of a #4
R.D.S. wire-wound rod. After the solvent had evaporated, the
composite coating was laminated to strips of silicone adhesive
("MacDermid" P-3) and the laminates were tested to determine
initial release, release after aging, and readhesion by means of
the procedures of Example 1. The results were as follows. Release:
Initial, 0.1 N/dm; aged, 0.2 N/dm. Readhesion: Initial, 38.1 N/dm;
aged, 39.4 N/dm. The control readhesion of a fresh adhesive was
approximately 39 N/dm.
EXAMPLE 14
This example describes the use of crosslinkable perfluoroether
polymer with pendant perfluoroether groups attached to the
backbone.
A coating solution consisting of 0.97% by weight of a 1.7:1.0
mixture of polyfluoropolyether bis(triethoxysilane) (Compound V)
and "Krytox" 1514 fluid along with 4% by weight (based on the total
polyfluoropolyether) dibutyltin diacetate as a cure catalyst in a
solvent consisting of 40% by volume 1,1,2-trichlorotrifluoroethane
("Freon" 113) and 60% by volume perfluorotributylamine ("FC-43")
was prepared. ##STR16##
This solution was coated on PET film (50 micrometers) by means of a
#4 R.D.S. wire-wound rod, and the coating was cured at 100.degree.
C. for five minutes and then allowed to stand overnight in air at
room temperature. The coating was tested with silicone adhesive
(DC-355) according to the procedure described in Example 2. The
results were as follows. Release: Initial 0.2 N/dm; aged 0.2N/dm.
Readhesion: Initial 78.7 N/dm; aged 78.3 N/dm. The control
readhesion of fresh adhesive was approximately 82 N/dm.
In the preceding examples, the trademarks and tradenames set forth
therein were obtained from the source listed in Table XIII.
TABLE XIII ______________________________________ Trademark or
trade name Source ______________________________________ MACu P-3
Tape MacDermid Co. Inc. "Freon" 113 E.I. DuPont de Nemours and
Company "Krytox" fluids E.I. DuPont de Nemours and Company "Kapton"
film E.I. DuPont de Nemours and Company "FC" series solvents
Minnesota Mining and Manufacturing Company Gravel Guard PU film
Minnesota Mining and Manufacturing Company DC-355 Dow-Corning Inc.
DC-7406 Dow-Corning Inc. GE-6574 General Electric Inc. "Cadox
TS-50" Noury Chemical Co. "Demnum" fluids Daikin Industries (Tokyo,
Japan) "Braycote" 815Z Bray Oil Co. PPG Model 1202 UV Pittsburgh
Plate Glass Co. "Darocur" 1173 EM Industries Inc.
______________________________________
Various modifications and alterations of this invention will become
apparent to those skilled in the art without departing from the
scope and spirit of this invention, and it should be understood
that this invention is not to be unduly limited to the illustrative
embodiments set forth herein.
* * * * *